The analysis of airborne nucleic acid molecules using conventional or real-time PCR methodologies is not currently applied worldwide due to a lack of sampling techniques and data extraction methods. However, there appear to be a variety of applications where such analytical approaches would be useful.
In all laboratories where the use of PCR technology is routinely used, a contamination problem commonly arises during the amplification of the same template DNA after a period of time. Due to aerosol generation (pipetting), the regular multiplication of the same nucleic acid regions results in amplicon contamination of the surrounding ambient air and wall surfaces. As a result, due to certain enrichment concentration over time, false-positive results occur since the airborne nucleic acids are able to enter those samples present in new analytical vessels. This situation has led to a required spatial separation of master mix preparations and the actual PCR being carried out, or to the necessary application of extra technical measures to prevent contamination of the preparations (i.e. PCR cabins). Such accumulated “contaminating” nucleic acid is to be expected not only in forensic laboratories, but also in laboratories dedicated to inspecting genetically modified food or feed. In the context of preventive quantitative analytics, it thus would seem desirable to routinely perform analysis of ambient air in order to determine the presence of contaminating nucleic acid fragments.
In addition to safeguarding quality-assurance procedures, another highly interesting field for airborne analytics emerges in the context of forensic analysis at crime scenes. When present in a room, every human being releases cellular material, and therefore clearly traceable genetic material, into the ambient air. Depending on the mode of human activity, said genetic material is released in lower or higher concentrations. Mere human presence leads to desquamation of the cornified stratified squamous epithelium of the skin, in addition to cellular material that is released into the ambient air due to coughing or sneezing reflexes via the mucous membranes; these secretions all contain personal nucleic acid components. If it were possible to reliably achieve enrichment of these genetic materials by air filtration, this would offer a unique forensic approach in addition to an effective searching strategy for detecting cellular or blood traces thus evidencing the presence of a specific person at a crime scene. However, to achieve this purpose, it would thus be necessary to directly filter large volumes of air on-site in order to deposit as much biological material as possible on a filter as derived from recently present persons. For example, air collection devices from the manufacturer Sartorius might enable a possibility of achieving sufficient biological concentrations on filter surfaces.